1. Field of the Invention
This invention relates to a disk drive capable of loading media of different specifications, specifically to a disk drive that can automatically identify the types of loaded media.
2. Description of the Related Art
A disk drive is used as a storage device that can handle mass data contained in a CD (compact Disc) or a DVD (Digital Versatile Disc) or the like for use in a computer, etc.
The CD and DVD have various types of specifications, for example, the CD-ROM (CD-Read Only Memory) or DVD-ROM (DVD-Read Only Memory) as the reproduction exclusive, the CD-R (CD-Recordable) or DVD-R (DVD-Recordable) that accepts writing only once, and the CD-RW (CD-ReWritable) or DVD-RAM (DVD-Random Access Memory) that accepts writing repeatedly. In accordance with the different specifications of the disks each, the disk drive suited to the specification of each disk is to be used.
The above different types of disks have a predetermined diameter, although the inner structures of the disks are different (positions of the recording layers). Accordingly, one disk drive can be made to comply with the disks of plural specifications. In this case, plural optical heads are provided in order to comply with the disks of different specifications.
FIG. 5 illustrates a flow chart, in which the individual specifications of the different disks are identified in a conventional disk drive. Here, in FIG. 5, the flow chart assumes a disk drive that is compatible to both the CD and the DVD.
As shown in FIG. 5, when a disk is loaded, the A/D converter and the focus driver are initialized to eliminate the offset components and the noise components (S100). At this moment, the focus correction unit is not locked yet, and the detection laser beams are not irradiated either.
After the initialization, the light emitting unit (light source) provided with the optical pickup (optical head) for CD irradiates the laser beams of the wavelength 780 nm toward the disk through a specified optical system (S101). The focus actuator (focus drive unit) energized drives the objective lens in the focusing direction in a low speed (bobbling motion) (S102). The detection signal of the reflected light returned from the disk surface is acquired, and the quantity of light (all the signals added: As) of the total reflected light and the level (RF envelope: Env) generated at the focused point during the bobbling motion are detected, and these signals are recorded in the memory (S103).
And, after the foregoing operation by the optical head for CD is completed, the light emitting unit (light source) provided with the optical pickup (optical head) for DVD irradiates the laser beams of the wavelength 650 nm toward the disk (S104). Next, the focus actuator drives the objective lens in the focusing direction (bobbling motion) (S105). And, all the signals added (As) and RF envelope (Env) are detected, which are recorded in the memory (S106). At the final stage, the specification of the disk loaded is identified (S107), and the optical head conformable to the specification of the disk loaded is selected, terminating the processing.
Thus, the conventional disk drive provided with the plural light sources of different wavelengths performs the identification of CD and the identification of DVD separately, which needs a very long time for the identification.
That is, in the identification of the CD and DVD, when both the disks are loaded, the focus actuator moves the optical head in the focusing direction to identify the disk; but at this moment, the movement of the optical head is very slow, and besides, when the plural optical heads are provided in order to make it possible to use the disks of different specifications, the identification of the CD and DVD needs double the time.
The present invention has been made in view of the foregoing problem, and it is an object of the invention to provide a disk drive that can identify the different specifications of the disks in a shorter time, while the disk drive is provided with different light sources of plural wavelengths.
According to one aspect of the invention, the disk drive is provided with a plurality of optical heads each provided with light emitting systems and light receiving systems and drive means that drive objective lenses for condensing lights on a media in the focusing direction and the tracking direction, in which the light emitting systems of a plurality of the optical heads are provided with light sources each capable of emitting lights of each different wavelengths. In this construction, when a media is loaded, the light emitting systems of a plurality of the optical heads simultaneously irradiate detection lights to the media, and the light receiving systems of the optical heads each detect reflected lights from the media. Further, the disk drive is provided with a memory that stores light receiving signals detected by the light receiving systems of the optical heads each and an identification means that judges values stored by the memory and identifies the type of the media.
According to another aspect of the invention, in the disk drive, a plurality of the optical heads each drive the objective lenses simultaneously in the focusing direction at least one time, and the memory stores the peak values of the total quantities of lights (all the signals added) of the reflected lights received by the light receiving systems of the optical heads each and the peak values of RF envelopes obtained when the detection lights are focused on the media.
The aforementioned implements make it unnecessary to separately operate the optical heads each and separately perform the processes, as the identification operation in the conventional disk drive, thereby reducing the time for identifying the type of the media.
According to another aspect of the invention, the identification means compares all the signals added with preset reference values to thereby judge whether the media is loaded or not.
According to another aspect of the invention, the peak values of all the signals added and/or the peak values of the RF envelopes are compared with the preset reference values to identify specifications of the media.
Further, in this invention, preferably the reference values are obtained from actual measurements and stored to be read out by the identification means.
Thus, according to the invention, the identification of the specifications of the CD and the DVD can be made in a shorter time, and moreover, the specifications of the disks, such as the CD-ROM, CD-R, CD-RW as the CD system, and the single layer DVD-ROM, double layer DVD-ROM, DVD-RAM as the DVD system can be identified in a shorter time.